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Steuer O, Liedke MO, Butterling M, Schwarz D, Schulze J, Li Z, Wagner A, Fischer IA, Hübner R, Zhou S, Helm M, Cuniberti G, Georgiev YM, Prucnal S. Evolution of point defects in pulsed-laser-melted Ge 1-xSn xprobed by positron annihilation lifetime spectroscopy. J Phys Condens Matter 2023; 36:085701. [PMID: 37931296 DOI: 10.1088/1361-648x/ad0a10] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Accepted: 11/06/2023] [Indexed: 11/08/2023]
Abstract
Direct-band-gap Germanium-Tin alloys (Ge1-xSnx) with high carrier mobilities are promising materials for nano- and optoelectronics. The concentration of open volume defects in the alloy, such as Sn and Ge vacancies, influences the final device performance. In this article, we present an evaluation of the point defects in molecular-beam-epitaxy grown Ge1-xSnxfilms treated by post-growth nanosecond-range pulsed laser melting (PLM). Doppler broadening - variable energy positron annihilation spectroscopy and variable energy positron annihilation lifetime spectroscopy are used to investigate the defect nanostructure in the Ge1-xSnxfilms exposed to increasing laser energy density. The experimental results, supported with ATomic SUPerposition calculations, evidence that after PLM, the average size of the open volume defects increases, which represents a raise in concentration of vacancy agglomerations, but the overall defect density is reduced as a function of the PLM fluence. At the same time, the positron annihilation spectroscopy analysis provides information about dislocations and Ge vacancies decorated by Sn atoms. Moreover, it is shown that the PLM reduces the strain in the layer, while dislocations are responsible for trapping of Sn and formation of small Sn-rich-clusters.
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Affiliation(s)
- O Steuer
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
- Institute of Materials Science, Technische Universität Dresden, Budapester Str. 27, 01069 Dresden, Germany
| | - M O Liedke
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - M Butterling
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - D Schwarz
- University of Stuttgart, Institute of Semiconductor Engineering, 70569 Stuttgart, Germany
| | - J Schulze
- Fraunhofer Institute for Integrated Systems and Device Technology IISB, 91058 Erlangen, Germany
| | - Z Li
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - A Wagner
- Institute of Radiation Physics, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - I A Fischer
- Experimental Physics and Functional Materials, Brandenburgische Technische Universität Cottbus-Senftenberg, 03046 Cottbus, Germany
| | - R Hübner
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - S Zhou
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - M Helm
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
- Center for Advancing Electronics Dresden, Technische Universität Dresden, Helmholtzstraße 18, 01062 Dresden, Germany
| | - G Cuniberti
- Institute of Materials Science, Technische Universität Dresden, Budapester Str. 27, 01069 Dresden, Germany
| | - Y M Georgiev
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
- Institute of Electronics, Bulgarian Academy of Sciences, 72, Tsarigradsko Chausse Blvd., 1784 Sofia, Bulgaria
| | - S Prucnal
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
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Steuer O, Schwarz D, Oehme M, Schulze J, Mączko H, Kudrawiec R, Fischer IA, Heller R, Hübner R, Khan MM, Georgiev YM, Zhou S, Helm M, Prucnal S. Band-gap and strain engineering in GeSn alloys using post-growth pulsed laser melting. J Phys Condens Matter 2022; 35:055302. [PMID: 36395508 DOI: 10.1088/1361-648x/aca3ea] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 11/17/2022] [Indexed: 06/16/2023]
Abstract
The pseudomorphic growth of Ge1-xSnxon Ge causes in-plane compressive strain, which degrades the superior properties of the Ge1-xSnxalloys. Therefore, efficient strain engineering is required. In this article, we present strain and band-gap engineering in Ge1-xSnxalloys grown on Ge a virtual substrate using post-growth nanosecond pulsed laser melting (PLM). Micro-Raman and x-ray diffraction (XRD) show that the initial in-plane compressive strain is removed. Moreover, for PLM energy densities higher than 0.5 J cm-2, the Ge0.89Sn0.11layer becomes tensile strained. Simultaneously, as revealed by Rutherford Backscattering spectrometry, cross-sectional transmission electron microscopy investigations and XRD the crystalline quality and Sn-distribution in PLM-treated Ge0.89Sn0.11layers are only slightly affected. Additionally, the change of the band structure after PLM is confirmed by low-temperature photoreflectance measurements. The presented results prove that post-growth ns-range PLM is an effective way for band-gap and strain engineering in highly-mismatched alloys.
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Affiliation(s)
- O Steuer
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - D Schwarz
- University of Stuttgart, Institute of Semiconductor Engineering, 70569 Stuttgart, Germany
| | - M Oehme
- University of Stuttgart, Institute of Semiconductor Engineering, 70569 Stuttgart, Germany
| | - J Schulze
- Fraunhofer Institute for Integrated Systems and Device Technology IISB, 91058 Erlangen, Germany
| | - H Mączko
- Department of Semiconductor Materials Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - R Kudrawiec
- Department of Semiconductor Materials Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wybrzeże Wyspiańskiego 27, 50-370 Wrocław, Poland
| | - I A Fischer
- Experimental Physics and Functional Materials, Brandenburgische Technische Universität Cottbus-Senftenberg, 03046 Cottbus, Germany
| | - R Heller
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - R Hübner
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - M M Khan
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - Y M Georgiev
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
- Institute of Electronics, Bulgarian Academy of Sciences, 72, Tsarigradsko Chausse Blvd, 1784 Sofia, Bulgaria
| | - S Zhou
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - M Helm
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
| | - S Prucnal
- Institute of Ion Beam Physics and Materials Research, Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstrasse 400, 01328 Dresden, Germany
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Kemmler R, Hübner R, Löhle A, Neubauer D, Voloshenko I, Schoop LM, Dressel M, Pronin AV. Free-carrier dynamics in Au 2Pb probed by optical conductivity measurements. J Phys Condens Matter 2018; 30:485403. [PMID: 30418951 DOI: 10.1088/1361-648x/aae7b1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We measured the optical reflectivity of the Dirac material Au2Pb in a broad frequency range (30-48 000 cm-1) for temperatures between 9 and 300 K. The optical conductivity, computed from the reflectivity, is dominated by free-carrier contributions from topologically trivial bulk bands at all temperatures. The temperature-independent total plasma frequency of these carriers is [Formula: see text] eV. Overall, optical response of Au2Pb is typically metallic with no signs of localization and bad-metal behavior.
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Affiliation(s)
- R Kemmler
- 1. Physikalisches Institut, Universität Stuttgart, 70569 Stuttgart, Germany
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Berencén Y, Prucnal S, Möller W, Hübner R, Rebohle L, Schönherr T, Khan MB, Wang M, Glaser M, Georgiev YM, Erbe A, Lugstein A, Helm M, Zhou S. Formation of n- and p-type regions in individual Si/SiO 2 core/shell nanowires by ion beam doping. Nanotechnology 2018; 29:474001. [PMID: 30192233 DOI: 10.1088/1361-6528/aadfb6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A method for cross-sectional doping of individual Si/SiO2 core/shell nanowires (NWs) is presented. P and B atoms are laterally implanted at different depths in the Si core. The healing of the implantation-related damage together with the electrical activation of the dopants takes place via solid phase epitaxy driven by millisecond-range flash lamp annealing. Electrical measurements through a bevel formed along the NW enabled us to demonstrate the concurrent formation of n- and p-type regions in individual Si/SiO2 core/shell NWs. These results might pave the way for ion beam doping of nanostructured semiconductors produced by using either top-down or bottom-up approaches.
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Affiliation(s)
- Y Berencén
- Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, D-01328 Dresden, Germany
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5
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Pelizzo MG, Corso AJ, Tessarolo E, Böttger R, Hübner R, Napolitani E, Bazzan M, Rancan M, Armelao L, Jark W, Eichert D, Martucci A. Morphological and Functional Modifications of Optical Thin Films for Space Applications Irradiated with Low-Energy Helium Ions. ACS Appl Mater Interfaces 2018; 10:34781-34791. [PMID: 30211532 DOI: 10.1021/acsami.8b13085] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Future space missions will operate in increasingly hostile environments, such as those in low-perihelion solar orbits and Jovian magnetosphere. This exploration involves the selection of optical materials and components resistant to the environmental agents. The conditions in space are reproduced on ground through the use of ion accelerators. The effects of He particles coming from the solar wind impinging on a gold thin film have been systematically investigated, considering absorbed doses compatible with the duration of the European Space Agency Solar Orbiter mission. Structural and morphological changes have been proved to be dependent not only on the dose but also on the irradiation flux. A predictive model of the variation of thin film reflectance has been developed for the case of lower flux irradiation. The results are discussed regarding reliability and limitations of laboratory testing. The outcomes are important to address the procedures for the space qualification tests of optical coatings.
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Affiliation(s)
- M G Pelizzo
- Istituto di Fotonica e Nanotecnologie , Consiglio Nazionale delle Ricerche , via Trasea 7 , 35131 Padova , Italy
- Dipartimento di Ingegneria dell'Informazione , Università degli Studi di Padova , via Gradenigo 6B , 35131 Padova , Italy
| | - A J Corso
- Istituto di Fotonica e Nanotecnologie , Consiglio Nazionale delle Ricerche , via Trasea 7 , 35131 Padova , Italy
| | - E Tessarolo
- Istituto di Fotonica e Nanotecnologie , Consiglio Nazionale delle Ricerche , via Trasea 7 , 35131 Padova , Italy
| | - R Böttger
- Institute of Ion Beam Physics and Materials Research Ion Beam Center , Helmholtz-Zentrum Dresden-Rossendorf , Bautzner Landstraße 400 , 01328 Dresden , Germany
| | - R Hübner
- Institute of Ion Beam Physics and Materials Research Ion Beam Center , Helmholtz-Zentrum Dresden-Rossendorf , Bautzner Landstraße 400 , 01328 Dresden , Germany
| | - E Napolitani
- Dipartimento di Fisica e Astronomia , Università degli Studi di Padova , via Marzolo 8 , 35131 Padova , Italy
| | - M Bazzan
- Dipartimento di Fisica e Astronomia , Università degli Studi di Padova , via Marzolo 8 , 35131 Padova , Italy
| | | | | | - W Jark
- Elettra-Sincrotrone Trieste , S.S. 14 Km 163.5 in Area Science Park , 34149 Trieste , Italy
| | - D Eichert
- Elettra-Sincrotrone Trieste , S.S. 14 Km 163.5 in Area Science Park , 34149 Trieste , Italy
| | - A Martucci
- Istituto di Fotonica e Nanotecnologie , Consiglio Nazionale delle Ricerche , via Trasea 7 , 35131 Padova , Italy
- Dipartimento di Ingegneria Industriale , Università degli Studi di Padova , via Marzolo 9 , 35131 Padova , Italy
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Pustogow A, Bories M, Löhle A, Rösslhuber R, Zhukova E, Gorshunov B, Tomić S, Schlueter JA, Hübner R, Hiramatsu T, Yoshida Y, Saito G, Kato R, Lee TH, Dobrosavljević V, Fratini S, Dressel M. Quantum spin liquids unveil the genuine Mott state. Nat Mater 2018; 17:773-777. [PMID: 30082905 DOI: 10.1038/s41563-018-0140-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 06/26/2018] [Indexed: 05/13/2023]
Abstract
The localization of charge carriers by electronic repulsion was suggested by Mott in the 1930s to explain the insulating state observed in supposedly metallic NiO. The Mott metal-insulator transition has been subject of intense investigations ever since1-3-not least for its relation to high-temperature superconductivity4. A detailed comparison to real materials, however, is lacking because the pristine Mott state is commonly obscured by antiferromagnetism and a complicated band structure. Here we study organic quantum spin liquids, prototype realizations of the single-band Hubbard model in the absence of magnetic order. Mapping the Hubbard bands by optical spectroscopy provides an absolute measure of the interaction strength and bandwidth-the crucial parameters that enter calculations. In this way, we advance beyond conventional temperature-pressure plots and quantitatively compose a generic phase diagram for all genuine Mott insulators based on the absolute strength of the electronic correlations. We also identify metallic quantum fluctuations as a precursor of the Mott insulator-metal transition, previously predicted but never observed. Our results suggest that all relevant phenomena in the phase diagram scale with the Coulomb repulsion U, which provides a direct link to unconventional superconductivity in cuprates and other strongly correlated materials.
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Affiliation(s)
- A Pustogow
- Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany.
| | - M Bories
- Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany
| | - A Löhle
- Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany
| | - R Rösslhuber
- Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany
| | - E Zhukova
- Moscow Institute of Physics and Technology (State University), Dolgoprudny, Russia
| | - B Gorshunov
- Moscow Institute of Physics and Technology (State University), Dolgoprudny, Russia
| | - S Tomić
- Institut za fiziku, Zagreb, Croatia
| | - J A Schlueter
- Division of Materials Research, National Science Foundation, Arlington, VA, USA
- Materials Science Division, Argonne National Laboratory, Argonne, IL, USA
| | - R Hübner
- Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany
- Biomedizinische Chemie, Institut für Klinische Radiologie und Nuklearmedizin, Universität Heidelberg, Mannheim, Germany
| | - T Hiramatsu
- Faculty of Agriculture, Meijo University, Nagoya, Japan
| | - Y Yoshida
- Faculty of Agriculture, Meijo University, Nagoya, Japan
- Division of Chemistry, Graduate School of Science, Kyoto University, Kyoto, Japan
| | - G Saito
- Faculty of Agriculture, Meijo University, Nagoya, Japan
- Toyota Physical and Chemical Research Institute, Nagakute, Japan
| | - R Kato
- Condensed Molecular Materials Laboratory, RIKEN, Wako-shi, Saitama, Japan
| | - T-H Lee
- Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
| | - V Dobrosavljević
- Department of Physics and National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
| | - S Fratini
- Institut Néel - CNRS and Université Grenoble Alpes, Grenoble, France
| | - M Dressel
- Physikalisches Institut, Universität Stuttgart, Stuttgart, Germany
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Nie WJ, Zhang YX, Yu HH, Li R, He RY, Dong NN, Wang J, Hübner R, Böttger R, Zhou SQ, Amekura H, Chen F. Plasmonic nanoparticles embedded in single crystals synthesized by gold ion implantation for enhanced optical nonlinearity and efficient Q-switched lasing. Nanoscale 2018; 10:4228-4236. [PMID: 29412199 DOI: 10.1039/c7nr07304f] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report on the synthesis of embedded gold (Au) nanoparticles (NPs) in Nd:YAG single crystals using ion implantation and subsequent thermal annealing. Both linear and nonlinear absorption of the Nd:YAG crystals have been enhanced significantly due to the embedded Au NPs, which is induced by the surface plasmon resonance (SPR) effect in the visible light wavelength band. Particularly, through a typical Z-scan system excited by a femtosecond laser at 515 nm within the SPR band, the nonlinear absorption coefficients of crystals with Au NPs have been observed to be nearly 5 orders of magnitude larger than that without Au NPs. This giant enhancement of nonlinear absorption properties is correlated with the saturable absorption (SA) effect, which is the basis of passive Q-switching or mode-locking for pulsed laser generation. In addition, the linear and nonlinear absorption enhancement could be tailored by varying the fluence of implanted Au+ ions, corresponding to the NP size and concentration modulation. Finally, the Nd:YAG wafer with embedded Au NPs has been applied as a saturable absorber in a Pr:LuLiF4 crystal laser cavity, and efficient pulsed laser generation at 639 nm has been realized, which presents superior performance to the MoS2 saturable absorber based system. This work opens an avenue to enhance and modulate the nonlinearities of dielectrics by embedding plasmonic Au NPs for efficient pulsed laser operation.
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Affiliation(s)
- W J Nie
- School of Physics, State Key Laboratory of Crystal Materials and Key Laboratory of Particle Physics and Particle Irradiation (MOE), Shandong University, Jinan 250100, P. R. China.
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8
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Vogel M, Fischer S, Maffert A, Hübner R, Scheinost AC, Franzen C, Steudtner R. Biotransformation and detoxification of selenite by microbial biogenesis of selenium-sulfur nanoparticles. J Hazard Mater 2018; 344:749-757. [PMID: 29156387 DOI: 10.1016/j.jhazmat.2017.10.034] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 09/27/2017] [Accepted: 10/16/2017] [Indexed: 05/27/2023]
Abstract
This study combines the interaction between the toxic oxyanions selenite and selenate and the plant growth promoting bacterium Azospirillum brasilense with a comprehensive characterization of the formed selenium particles. As selenium is an essential trace element, but also toxic in high concentrations, its state of occurrence in nature is of major concern. Growth of the bacterium was affected by selenite (1-5mM) only, observable as a prolonged growth lag-phase of 3days. Subsequently, selenite reduction occurred under aerobic conditions resulting in extracellularly formed insoluble Se0 particles. Complementary studies by microscopic and spectroscopic techniques revealed the particles to be homogeneous and stable Se8-nSn structured spheres with an average size of 400nm and highly negative surface charge of -18mV in the neutral pH range. As this is the first study showing Azospirillum brasilense being able to biotransform selenite to selenium particles containing a certain amount of sulfur, even if environmental waters supplemented with selenite were used, they may significantly contribute to the biogeochemical cycling of both elements in soil as well as to their soil-plant transfer. Therefore, microbial biotransformation of selenite under certain circumstances may be used for various bio-remediation and bio-technological applications.
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Affiliation(s)
- M Vogel
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, Bautzner Landstrasse 400, D-01328 Dresden, Germany; Helmholtz-Zentrum Dresden-Rossendorf e.V., Helmholtz Institute Freiberg for Resource Technology, Bautzner Landstrasse 400, D-01328 Dresden, Germany.
| | - S Fischer
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, Bautzner Landstrasse 400, D-01328 Dresden, Germany.
| | - A Maffert
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, Bautzner Landstrasse 400, D-01328 Dresden, Germany; Helmholtz-Zentrum Dresden-Rossendorf e.V., Helmholtz Institute Freiberg for Resource Technology, Bautzner Landstrasse 400, D-01328 Dresden, Germany.
| | - R Hübner
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Ion-Beam Physics and Materials Research, Bautzner Landstrasse 400, D-01328 Dresden, Germany.
| | - A C Scheinost
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, Bautzner Landstrasse 400, D-01328 Dresden, Germany; European Synchrotron Radiation Facility, Rossendorf Beamline, BP 220, F-38043 Grenoble, France.
| | - C Franzen
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, Bautzner Landstrasse 400, D-01328 Dresden, Germany.
| | - R Steudtner
- Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Resource Ecology, Bautzner Landstrasse 400, D-01328 Dresden, Germany.
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Affiliation(s)
| | - C. Lämmel
- Fraunhofer IKTS Dresden; Dresden 01277 Germany
| | - R. Hübner
- Helmholtz-Zentrum Dresden-Rossendorf; Dresden 01328 Germany
| | - U. Gierth
- Fraunhofer IKTS Dresden; Dresden 01277 Germany
| | - A. Michaelis
- Fraunhofer IKTS Dresden; Dresden 01277 Germany
- Institut für Werkstoffwissenschaft; TU Dresden; Dresden 01069 Germany
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10
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Buljan M, Radić N, Sancho-Paramon J, Janicki V, Grenzer J, Bogdanović-Radović I, Siketić Z, Ivanda M, Utrobičić A, Hübner R, Weidauer R, Valeš V, Endres J, Car T, Jerčinović M, Roško J, Bernstorff S, Holy V. Production of three-dimensional quantum dot lattice of Ge/Si core-shell quantum dots and Si/Ge layers in an alumina glass matrix. Nanotechnology 2015; 26:065602. [PMID: 25605224 DOI: 10.1088/0957-4484/26/6/065602] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report on the formation of Ge/Si quantum dots with core/shell structure that are arranged in a three-dimensional body centered tetragonal quantum dot lattice in an amorphous alumina matrix. The material is prepared by magnetron sputtering deposition of Al2O3/Ge/Si multilayer. The inversion of Ge and Si in the deposition sequence results in the formation of thin Si/Ge layers instead of the dots. Both materials show an atomically sharp interface between the Ge and Si parts of the dots and layers. They have an amorphous internal structure that can be crystallized by an annealing treatment. The light absorption properties of these complex materials are significantly different compared to films that form quantum dot lattices of the pure Ge, Si or a solid solution of GeSi. They show a strong narrow absorption peak that characterizes a type II confinement in accordance with theoretical predictions. The prepared materials are promising for application in quantum dot solar cells.
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Affiliation(s)
- M Buljan
- Rudjer Bošković Institute, Bijenička cesta 54,10000 Zagreb, Croatia
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11
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Gundogdu S, Ozen ES, Hübner R, Heinig KH, Aydinli A. Laser induced sponge-like Si in Si-rich oxides for photovoltaics. Opt Express 2013; 21:24368-24374. [PMID: 24104345 DOI: 10.1364/oe.21.024368] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We show that a sponge-like structure of interconnected Si nanowires embedded in a dielectric matrix can be obtained by laser annealing of silicon rich oxides (SRO). Due to quantum confinement, the large bandgap displayed by these percolated nanostructures can be utilized as a tandem stage in 3rd generation thin-film solar cells. Well passivated by the SiO₂ dielectric matrix, they are expected to overcome the difficulty of carrier separation encountered in the case of isolated crystalline quantum dots. In this study PECVD grown SRO were irradiated by a cw Ar⁺ laser. Raman spectroscopy has been used to assess the crystallinity of the Si nanostructures and thus to optimize the annealing conditions as dwell times and power densities. In addition, Si plasmon imaging in the transmission electron microscope was applied to identify the sponge-like structure of phase-separated silicon.
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12
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Hovakimyan M, Maass F, Petersen J, Holzmann C, Witt M, Lukas J, Frech MJ, Hübner R, Rolfs A, Wree A. Combined therapy with cyclodextrin/allopregnanolone and miglustat improves motor but not cognitive functions in Niemann-Pick Type C1 mice. Neuroscience 2013; 252:201-11. [PMID: 23948640 DOI: 10.1016/j.neuroscience.2013.08.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 07/31/2013] [Accepted: 08/01/2013] [Indexed: 12/21/2022]
Abstract
Niemann-Pick Type C1 (NPC1) is an autosomal recessive disorder characterized by the accumulation of cholesterol and glycosphingolipids. Combination-treatment utilizing cyclodextrin, allopregnanolone and miglustat (CYCLO/ALLO/miglustat) can ameliorate NPC1 disease in a mutant mouse model. The present study was designed to add behavioral analysis in NPC1 mutant mice upon CYCLO/ALLO/miglustat therapy. NPC1 mutant (BALB/cJ NPC1NIH) and control mice were used. For the combination treatment mice were injected with CYCLO/ALLO weekly, starting at P7. The miglustat injection was performed daily from P10 till P23. Starting at P23, miglustat was added to the powdered chow. For the sham treatment of control and mutant mice the same schedule was used with 0.9% NaCl injection. Locomotor activity was assessed in open field, elevated plus maze and accelerod tests. For assessment of spatial learning and memory the Morris water maze test was conducted. Electron microscopy has been performed to support the behavioral data. The sham-treated mutant mice exhibited motor impairments in all performed tests. In the water maze the sham-treated mutants exhibited impairment in remembering the location of the hidden platform. CYCLO/ALLO/miglustat treatment positively influenced motor dysfunction: total distance and number of visits significantly increased, and accelerod performance improved. The spatial learning, however, did not benefit from therapy. At the morphological level, an excessive accumulation of electron-dense material was seen in the cerebellar Purkinje cells of mutant mice. A regression of these autophagosomal inclusions was seen upon therapy. CYCLO/ALLO/miglustat therapy ameliorates motor but not cognitive deficits in NPC1 mutant mice, suggesting unequal vulnerability of different brain areas to the treatment.
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Affiliation(s)
- M Hovakimyan
- Institute of Anatomy, University of Rostock, Gertrudenstrasse 9, D-18057 Rostock, Germany.
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13
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Van der Linden P, Lambermont M, Dierick A, Hübner R, Benoit Y, De Backer D, De Paep R, Ferrant A, Latinne D, Muylle L, Selleslag D, Szabo B, Thomas I, Vandekerckhove B, Deneys V. Recommendations in the event of a suspected transfusion-related acute lung injury (TRALI). Acta Clin Belg 2012; 67:201-8. [PMID: 22897069 DOI: 10.2143/acb.67.3.2062656] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The following recommendations, which aim at improving the clinical diagnosis ofTRALI and the laboratory investigations that can support it, were drawn up by a working group of the Superior Health Council. TRALI is a complication of blood transfusion that is both serious and underreported. Systematic reporting may help to develop preventive actions. Therefore, the Superior Health Council recommends that there should be a more stringent surveillance of patients who receive a blood component transfusion. The clinician should pay very close attention to any change in the patient's respiratory status (cf. dyspnoea and arterial desaturation), which should be notified systematically to the haemovigilance contact person in the hospital.
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Affiliation(s)
- P Van der Linden
- Service d'Anesthésiologie, CHU Brugmann-HUDERF, Université Libre de Bruxelles (ULB), Belgium.
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14
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Delforge M, Farber CM, Spath P, Kaveri S, Witte T, Misbah SA, Hübner R, Haerynck F, Latinne D, Muylle L, Toungouz M, Deneys V. Recommended indications for the administration of polyclonal immunoglobulin preparations. Acta Clin Belg 2012; 66:346-60. [PMID: 22145269 DOI: 10.2143/acb.66.5.2062586] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The following recommendations, which aim at standardising and rationalising the clinical indications for administering polyclonal immunoglobulins in Belgium, were drawn up by a working group of the Superior Health Council. To this end, the Superior Health Council organised an expert meeting devoted to"Guidelines for the use of immunoglobulins". The experts discussed the indications for immunoglobulin use, the'ideal'immunoglobulin preparation, its mechanisms of action, the practical issues involved in administering immunoglobulins and their potential side effects. The recommendations formulated by the experts were validated by the Superior Health Council working group with the purpose of harmonising immunoglobulin use in Belgium
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Affiliation(s)
- M Delforge
- Afdeling Hematologie, Universitaire Ziekenhuizen Leuven (KUL), Leuven, Belgium.
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15
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Binder D, Hübner R, Temmesfeld-Wollbrück B, Beinert T, Schlattmann P. Lung toxicity among patients with cancer treated with a combination of docetaxel and gemcitabine: A meta-analysis of clinical studies. J Clin Oncol 2011. [DOI: 10.1200/jco.2011.29.15_suppl.e19544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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16
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Binder D, Buckendahl A, Hübner R, Temmesfeld-Wollbrück B, Suttorp N. Erlotinib bei Patienten mit fortgeschrittenem nichtkleinzelligem Lungenkarzinom: Rolle von Dosisreduktionen. Pneumologie 2011. [DOI: 10.1055/s-0031-1272214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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17
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Kim Y, Zahlten J, Hocke A, Suttorp N, Hippenstiel S, Hübner R. Streptococcus pneumoniae induziert über die Abnahme des intrazellulären Glutathione einen oxidativen Stress in den Atemwegsepithelien. Pneumologie 2011. [DOI: 10.1055/s-0031-1272053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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18
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Binder D, Hübner R, Temmesfeld-Wollbrück B, Suttorp N. Paronychie als neuer prädiktiver Faktor bei Patienten mit fortgeschrittenem nichtkleinzelligem Lungenkarzinom unter Behandlung mit Erlotinib. Pneumologie 2011. [DOI: 10.1055/s-0031-1272216] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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19
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Binder D, Beinert T, Hübner R, Temmesfeld-Wollbrück B, Suttorp N. Dose modifications, dose-effect relationship, and adverse effects in patients with advanced non-small cell lung cancer treated with erlotinib. J Clin Oncol 2010. [DOI: 10.1200/jco.2010.28.15_suppl.e18113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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20
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Hübner R, Belger A, Meyer DC, Paufler P, Polyakova IG. Crystallisation of caesium borosilicate glasses with approximate boroleucite composition. Z KRIST-CRYST MATER 2009. [DOI: 10.1524/zkri.217.6.223.22809] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Abstract
Crystallisation and annealing behaviour of two caesium borosilicate glass samples with approximate boroleucite composition were characterised by means of differential scanning calorimetry measurements as well as X-ray powder diffraction investigations with subsequent profile fitting of the observed patterns according to the Rietveld and/or Pawley method. While one sample crystallised primarily in an orthorhombic phase (a = 6.592(3) Å, b = 11.825(5) Å, c = 12.620(6) Å; possible space groups: Pmc21 ((26), setting: P21
am), Pma2 (28) and Pmma ((51), setting: Pmam)) which has been unknown until now and transformed irreversibly into the well-known cubic boroleucite phase at T ≈ 850 °C, cubic caesium boroleucite (space group: Ia3̅d (230)) was crystallised directly from the other sample. In this case, the orthorhombic phase was metastable. At the onset temperature of glass crystallisation Tx
, on = 770 °C, it existed only for about 75 min. The change of the lattice parameter a of the cubic unit cell of caesium boroleucite in the course of the thermal treatments was explained by the alteration of the size of the TO4 tetrahedra (T = Si, B).
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21
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De Backer D, Vandekerckhove B, Stanworth S, Williamson L, Hermans C, Van der Linden P, Hübner R, Baele P, Jochmans K, Ferrant A, Lambermont M, Muylle L, Toungouz M. Guidelines for the use of fresh frozen plasma. Acta Clin Belg 2008; 63:381-90. [PMID: 19170354 DOI: 10.1179/acb.2008.079] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Recommendations, which aim at standardising and rationalising clinical indications for the transfusion of fresh frozen plasma (FFP) in Belgium, were drawn up by a working group of the Superior Health Council. For this purpose the Superior Health Council organised an expert meeting devoted to "Transfusion Guidelines: Pathogen reduction, products and indications for the transfusion of plasma" in collaboration with the Belgian Haematological Society.The experts discussed the indications for the transfusion of FFP, pathogen reduction for FFP and the practical issues of administering FFP and plasma-derived concentrates. The recommendations formulated by the experts were validated by the working group with the purpose of harmonising FFP transfusion in Belgian hospitals.
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Affiliation(s)
- D De Backer
- Service Soins Intensifs, Hôpital universitaire Erasme (ULB), Bruxelles, Belgique.
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22
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Baele PL, Muylle L, Noens L, Gulliksson H, Brands A, Isbister J, Van der Linden P, Hübner R, Berneman Z, Lamy M, Ferrant A, Lambermont M, Sondag D. Guidelines for the transfusion of red cells. Acta Clin Belg 2008; 63:301-12. [PMID: 19186562 DOI: 10.1179/acb.2008.060] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The following recommendations, which aim at standardising and rationalising clinical indications for the transfusion of red cells in Belgium, were drawn up by a working group of the Superior Health Council. To this end, the Superior Health Council organised an expert meeting devoted to "Guidelines for the transfusion of red cells" in collaboration with the Belgian Hematological Society. The experts discussed the indications for red cell transfusions, the ideal red cell concentrate, the practical issues of administering red cells, and red cell transfusions in patients in a critical condition. The recommendations formulated by the experts were validated by the working group with the purpose of harmonising red cell transfusion in Belgian hospitals.
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Affiliation(s)
- P L Baele
- Service d'Anesthésiologie, Cliniques universitaires Saint-Luc (UCL), Bruxelles, Belgique
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23
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Bosly A, Muylle L, Noens L, Pietersz R, Heims D, Hübner R, Selleslag D, Toungouz M, Ferrant A, Sondag D. Guidelines for the transfusion of platelets. Acta Clin Belg 2007; 62:36-47. [PMID: 17451144 DOI: 10.1179/acb.2007.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Recommendations aiming at standardising and rationalising clinical indications for the transfusion of platelets in Belgium were drawn up by a working group of the Superior Health Council. To this end the Superior Health Council organised an expert meeting devoted to "Guidelines for the transfusion of platelets" in collaboration with the Belgian Hematological Society. The experts discussed the indications for platelet transfusions, the ideal platelet concentrate and the optimal platelet transfusion therapy. The recommendations prepared by the experts were validated by the working group with the purpose of harmonising platelet transfusion in Belgian hospitals.
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Affiliation(s)
- A Bosly
- Service d'Hématologie, Hôpital universitaire Mont-Godinne (UCL), Yvoir, Belgique
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24
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Hübner R, Reiche R, Hecker M, Mattern N, Hoffmann V, Wetzig K, Heuer H, Wenzel C, Engelmann HJ, Zschech E. Void formation in the Cu layer during thermal treatment of SiNx/Cu/Ta73Si27/SiO2/Si systems. Cryst Res Technol 2004. [DOI: 10.1002/crat.200410316] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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25
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Brachwitz W, Hübner R, Pritzkow W. Diels-Alder-Reaktionen. III. Kinetische Untersuchungen über die Gasphasepyrolyse von Homo- und Mischdimeren aliphatischer und cycloaliphatischer Dienkohlenwasserstoffe. ACTA ACUST UNITED AC 2004. [DOI: 10.1002/prac.19753170316] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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26
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27
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Kozłowska M, Reiche R, Oswald S, Vinzelberg H, Hübner R, Wetzig K. Quantitative ARXPS investigation of systems with ultrathin aluminium oxide layers. SURF INTERFACE ANAL 2004. [DOI: 10.1002/sia.1988] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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28
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Hübner R, Hecker M, Mattern N, Hoffmann V, Wetzig K, Engelmann HJ, Zschech E. Comparison of the annealing behavior of thin Ta films deposited onto Si and SiO2 substrates. Anal Bioanal Chem 2004; 379:568-75. [PMID: 15067495 DOI: 10.1007/s00216-004-2602-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2004] [Revised: 03/01/2004] [Accepted: 03/15/2004] [Indexed: 10/26/2022]
Abstract
Structural changes at annealing temperatures (T(an)) of 500-1,100 degrees C were investigated for thin Ta films which were sputter-deposited onto pure Si substrates and onto thermally oxidized Si. In the as-deposited state, the Ta layers predominantly consist of metastable tetragonal beta-Ta, whereby the [001] texture is independent of the substrate material. At lower annealing temperatures, the microstructural evolution is essentially the same for both Ta films. Incorporation of O atoms causes an increase of the intrinsic compressive stress, and diffusion of C atoms into the Ta layer leads to the formation of Ta(2)C. Additionally, a partial transformation of the original beta-Ta phase into a second phase with tetragonal unit cell (denoted as beta'-Ta) occurs. For the Ta/Si system, the formation of a Ta-Si intermixing layer is initiated at T(an)=550 degrees C, and nucleation of crystalline TaSi(2) occurs at T(an)=620 degrees C. The formation of a second Ta silicide was not detected up to T(an)=900 degrees C. In the case of the Ta film deposited onto the SiO(2) substrate, the metastable beta-Ta and the beta'-Ta transform completely into the thermodynamically stable cubic alpha-Ta at T(an)=750 degrees C. A marked reaction with the substrate indicated by the formation of Ta(2)O(5) and Ta(5)Si(3) occurs at T(an)=1,000 degrees C.
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Affiliation(s)
- R Hübner
- Leibniz Institute for Solid State and Materials Research Dresden, Helmholtzstrasse 20, 01069 Dresden, Germany.
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29
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Abstract
BACKGROUND Adenoidectomy, with or without tonsillectomy, remains as one of the most common surgical procedures. This study was undertaken to determine whether or not the criteria for adenoidectomy based on an inpatient basis in our hospital have to be revised and to evaluate the incidence of postoperative bleeding. MATERIAL AND METHODS The data of 470 patients who underwent adenoidectomy during 1 year were analyzed in a prospective study. Age <1 year; age >16 years; underlying diseases that put the patient at increased pre-or postoperative cardiopulmonary, metabolic or general risk; >20 minutes driving time between hospital and home, lack of compliance; request of the patients/parents were criteria for adenoidectomy to be performed as an inpatient procedure. Due to the rarity of postoperative bleeding the rate of post-adenoidectomy hemorrhage was calculated in a retrospective study on the basis of the data of 8131 patients who had undergone adenoidectomy. RESULTS A total of 249 patients underwent adenoidectomy on an outpatient basis (53%). Two patients required surgical treatment for postoperative bleeding under general anesthesia (0.43%), one of whom was initially scheduled for outpatient surgery. The parents of 17 children initially scheduled for outpatient surgery refused to take responsibility of postoperative care on the day of surgery. These children were admitted. Inpatient observation was scheduled in most cases because of the distance to the hospital (115 patients) or underlying diseases (7 patients). The rate of post-adenoidectomy hemorrhage in our retrospective study was 0.23%. There was only one adult with repeated bleeding on the day of surgery and 6 days postoperatively. 15 of 19 episodes of bleeding occurred on the day of surgery, the latest episode 6 days postoperatively. There was no case with lethal outcome. No blood transfusions or major surgical procedures at the neck were required to stop the bleeding. CONCLUSIONS Inpatient observation should be considered in patients with underlying general diseases, postoperative bleeding, poor compliance or request of the patients/parents. Age, general risk of post-adenoidectomy hemorrhage and distance to the hospital are not criteria significant enough to indicate inpatient observation in patients who undergo adenoidectomy.
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Affiliation(s)
- J P Windfuhr
- Klinik für Hals-Nasen-Ohrenkrankheiten, Kopf-Hals- und Plastische Gesichtschirurgie, Malteser-Krankenhaus St. Anna, Duisburg.
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30
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Lübben G, Hübner R. [Drug interactions as exemplified by thiazolidinediones (glitazones). Commentary on the publication of Ulrich Klotz and Dietmar Sailer, "Drug interactions--their impact on safe drug therapy in the example of the new thiazolidinedione group (glitazone)"Arzneimittelforschung. 2001 Feb;51(2):112-7]. Arzneimittelforschung 2002; 51:1015-6; discussion 1017. [PMID: 11799839] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Affiliation(s)
- G Lübben
- Takeda Pharma GmbH Viktorieaallee 3-5 52066 Aachen.
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31
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Kienle E, Hillger H, Hübner R, Jost V. Prospektive, randomisierte Studie zur Pharmakodynamik, Pharmakokinetik und Bioäquivalenz des GnRH-Analogons Leuprorelinacetat als 1- und 3-Monats-Depot bei Uterus myomatosus. Geburtshilfe Frauenheilkd 2001. [DOI: 10.1055/s-2001-18369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022] Open
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32
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Kienle E, Hillger H, Hübner R, Jost V. Prospektive, randomisierte Studie zur Wirksamkeit und Verträglichkeit des GnRH-Analogons Leuprorelinacetat als 1- und 3-Monats-Depot bei Patientinnen mit Uterus myomatosus. Geburtshilfe Frauenheilkd 2001. [DOI: 10.1055/s-2001-18375] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022] Open
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33
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Hübner R, Fuchs W. [Pharmacologic basics: the effect of AT1 receptor antagonists]. Pharm Unserer Zeit 2001; 30:304-7. [PMID: 11499255 DOI: 10.1002/1615-1003(200107)30:4<304::aid-pauz304>3.0.co;2-u] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- R Hübner
- TAKEDA PHARMA GMBH Viktoriaallee 3-5 52066 Aachen.
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34
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Abstract
Guided Search 2 (GS2) is currently one of the most detailed models of visual search and has been used to predict search times for different stimulus conditions by means of detailed computer simulations. The present article goes a step further and presents formulas that allow for the calculation of the search times and their variances. Moreover, these formulas can be applied to fit GS2 to data. An example is provided in which GS2 is fitted to search functions representing search asymmetries.
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Affiliation(s)
- R Hübner
- Universität Konstanz, Fachbereich Psychologie, Germany.
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35
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Hübner R, Futterer T, Steinhauser M. On attentional control as a source of residual shift costs: evidence from two-component task shifts. J Exp Psychol Learn Mem Cogn 2001; 27:640-53. [PMID: 11394671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
It is widely assumed that supervisory or attentional control plays a role only in the preparatory reconfiguration of the mental system in task shifting. The well-known fact that residual shift costs are still present even after extensive preparation is usually attributed to passive mechanisms such as cross talk. The authors question this view and suggest that attentional control is also responsible for residual shift costs. The authors hypothesize that, under shift conditions, tasks are executed in a controlled mode to guarantee reliable performance. Consequently, the control of 2 task components should require more resources than the control of only 1. A series of 4 experiments with 2-component tasks was conducted to test this hypothesis. As expected, more residual shift costs were observed when 2 components rather than 1 varied across trials. Interference effects and sequential effects could not account for these results.
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Affiliation(s)
- R Hübner
- Fachbereich Psychologie, Universität Konstanz, Germany.
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36
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Abstract
In this study, the effects of familiarity on visual search were investigated. To avoid any confounding between familiarity and visual-feature differences between item pairs, Ns and mirror-Ns were presented as target and as distractors to a group of German participants and to a group of Slavic participants. For the Germans only N was familiar, whereas for the Slavs both N and mirror-N were familiar. The results show that search was difficult only when the Germans had to find an N among mirror-Ns. In any other case, search was efficient. Therefore, our results demonstrate that, contrary to earlier suggestions, search for a familiar item among familiar distractors can be easy. This supports the hypothesis that familiarity improves distractor grouping. However, the data are also compatible with the idea that letters are standard or basic features, which implies that basic features can be learned.
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37
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Abstract
In a series of four experiments, we investigated the conditions under which target-absent responses are faster than target-present responses in visual search. Previous experiments have shown that such an absent-advantage occurs mainly for homogeneous distractors arranged in a regular pattern. From these results, it has been concluded that the absent-advantage is due to perceptual processes, such as grouping by similarity. Our data show that such processes are not sufficient. Rather, the absent-advantage is the result of interactions between perceptual and decisional processes. Certain perceptual conditions, such as randomizing stimulus patterns, lead to specific criteria settings that produce an absent-advantage. That such an account can explain our main results is demonstrated by modeling our data with a modified version of the Guided Search 2 model.
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Affiliation(s)
- R Hübner
- Universität Konstanz, Fach D29, D-78457 Konstanz, Germany.
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38
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Elmfeldt D, George M, Hübner R, Olofsson B. Candesartan Cilexetil, a Novel Angiotensin II Antagonist, Provides Dose-dependent Antihypertensive Effect with Maintained Tolerability. Blood Press 2000; 9:54. [PMID: 28425799 DOI: 10.1080/080370500439272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Candesartan is a new angiotensin II type 1 (AT 1 ) receptor blocker that binds tightly to and dissociates slowly from the AT 1 -receptor. It is administered as a prodrug, candesartan cilexetil, which is completely converted to the active compound, candesartan, during absorption in the gastrointestinal tract. Placebo-controlled studies have shown that candesartan cilexetil is an effective antihypertensive drug. The individual studies, however, lacked the statistical power to assess the dose-response relationship with high precision. A more precise estimate of the effect of different doses may be achieved by pooling similar studies in a meta-analysis. The primary objective of this meta-analysis was to determine the dose-response relationship for the antihypertensive effect of candesartan cilexetil. Six European randomized, double-blind, placebo-controlled, dose-response studies with candesartan cilexetil were reported by 30 September 1996. These studies enrolled similar patients (primary hypertension with a sitting diastolic blood pressure [DBP] of 95-114 mmHg after a placebo run-in period) and had a similar design (parallel groups and fixed doses). The doses investigated ranged from 2 to 16 mg once daily. All doses were not given in every study, but all studies investigated at least two different doses of candesartan cilexetil. The duration of the double-blind phase varied between studies, but was at least 4 weeks (range: 4-12 weeks). The variable of primary interest was sitting DBP measured 24 h after dose (trough effect). Each dose of candesartan was analysed separately, and compared with placebo data only from those studies in which that dose was given. The analysis was performed using an analysis of covariance model. Placebo-corrected estimated mean blood pressure reductions from baseline (randomization) to the end of the study and the 95% confidence intervals for the true mean reductions were calculated for each dose. In total, 1498 hypertensive patients were randomized, of whom 1482 provided efficacy data and were included in the analysis. The vast majority of patients (99%) were of Caucasian origin. The placebo-corrected reductions in sitting DBP and sitting systolic blood pressure (SBP) achieved with the different doses of candesartan cilexetil are shown in the Table. Reductions in blood pressure were dose-related, and age or gender did not influence the antihypertensive effect of candesartan cilexetil. Furthermore, blood pressure reductions achieved in the standing position were similar to those in the sitting position, i.e. there was no indication of an abnormal orthostatic response during treatment with candesartan cilexetil. Heart rate was not significantly influenced by candesartan cilexetil. Adverse events occurred in a similar proportion of patients treated with placebo or candesartan cilexetil and did not increase with the dose. Candesartan cilexetil was equally well tolerated in young and elderly patients and in men and women. Thus, in European patients with mild to moderate hypertension, candesartan cilexetil provides a clinically significant, dose-dependent, antihypertensive effect in doses ranging from 4 to 16 mg once daily. The optimal maintenance doses of candesartan cilexetil appear to be 8 or 16 mg once daily in most patients.
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Affiliation(s)
- D Elmfeldt
- a Astra Hassle, Clinical R&D, Molndal, Sweden
| | | | - R Hübner
- b Takeda Europe R&D Centre, Frankfurt, Germany
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39
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Hübner R, Backer G. Perceiving spatially inseparable objects: evidence for feature-based object selection not mediated by location. J Exp Psychol Hum Percept Perform 1999; 25:1556-67. [PMID: 10641311 DOI: 10.1037/0096-1523.25.6.1556] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In 4 experiments, stimulus elements were arranged into an LED-like array, and letters were defined within the array by feature similarity between the elements with respect to color and form. These stimuli allowed the display of a target and a distractor letter simultaneously at the same location. They were spatially inseparable but could be separated in feature space. Participants had to identify the letter on a prespecified feature dimension (color or form). As a result, the distractors produced specific compatibility effects. This showed that nontarget features could not be ignored at an early stage (i.e., that color and form were processed automatically and in parallel up to a high stage). The target was selected from the resulting objects according to the prespecified feature dimension. Results demonstrate that object selection is possible without selecting absolute spatial arrays.
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Affiliation(s)
- R Hübner
- Department of Psychology, Technische Universität Braunschweig, Germany
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40
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Lapière K, Dhaene K, Matthieu L, Hübner R, Lambert J, Van Marck E. Diagnosis of cutaneous T-cell lymphoma detecting T-cell receptor gamma chain gene monoclonality by denaturing gradient gel electrophoresis. Acta Clin Belg 1999; 54:65-71. [PMID: 10394643] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
Cutaneous T-cell lymphomas represent a group of malignant lymphoproliferative disorders characterised by the occurrence of a monoclonal population of T-lymphocytes. Diagnosis of early stages of this disease is a difficult challenge for both the dermatologist and the dermatopathologist. With the aid of the polymerase chain reaction it is possible to amplify specific regions of the T-cell receptor gamma gene. The amplification products can then be separated by denaturing gradient gel electrophoresis in order to detect a monoclonal population of T-lymphocytes in the infiltrate. We studied 4 patients with the clinicopathologic diagnosis of mycosis fungoides and 2 patients diagnosed as large plaque parapsoriasis. A monoclonal population was detected in 3 of the 4 mycosis fungoides cases and in 1 of the patients with large plaque parapsoriasis. This indicates that our analysis can help us establishing a diagnosis, and it can also help us to identify patients with a possible early stage of the disease, which clinically or histologically is not yet recognised as such.
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MESH Headings
- Aged
- Diagnosis, Differential
- Electrophoresis, Agar Gel
- Gene Amplification
- Gene Rearrangement, gamma-Chain T-Cell Antigen Receptor/genetics
- Genes, T-Cell Receptor gamma/genetics
- Humans
- Lymphoma, T-Cell, Cutaneous/diagnosis
- Lymphoma, T-Cell, Cutaneous/genetics
- Lymphoma, T-Cell, Cutaneous/pathology
- Middle Aged
- Mycosis Fungoides/diagnosis
- Mycosis Fungoides/genetics
- Mycosis Fungoides/pathology
- Parapsoriasis/diagnosis
- Parapsoriasis/genetics
- Parapsoriasis/pathology
- Polymerase Chain Reaction
- Skin Neoplasms/diagnosis
- Skin Neoplasms/genetics
- Skin Neoplasms/pathology
- T-Lymphocytes/pathology
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Affiliation(s)
- K Lapière
- Universitaire Instelling Antwerpen (UIA), Departement Geneeskunde, België
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41
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Lapière K, Dhaene K, Matthieu L, Hübner R, Lambert J, Marck EV. Diagnosis of Cutaneous T-Cell Lymphoma Detecting T-Cell Receptor γ Chain Gene Monoclonality By Denaturing Gradient Gel Electrophoresis. Acta Clin Belg 1999; 54:65-71. [PMID: 27689951 DOI: 10.1080/17843286.1999.11754211] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Cutaneous T-cell lymphomas represent a group of malignant lymphoproliferative disorders characterised by the occurrence of a monoclonal population of T-lymphocytes. Diagnosis of early stages of this disease is a difficult challenge for both the dermatologist and the dermatopathologist. With the aid of the polymerase chain reaction it is possible to amplify specific regions of the T-cell receptor gamma gene. The amplification products can then be separated by denaturing gradient gel electrophoresis in order to detect a monoclonal population of T-lymphocytes in the infiltrate. We studied 4 patients with the clinicopathologic diagnosis of mycosis fungoides and 2 patients diagnosed as large plaque parapsoriasis. A monoclonal population was detected in 3 of the 4 mycosis fungoides cases and in 1 of the patients with large plaque parapsoriasis. This indicates that our analysis can help us establishing a diagnosis, and it can also help us to identify patients with a possible early stage of the disease, which clinically or histologically is not yet recognised as such.
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Abstract
BACKGROUND Gradual telomere erosion eventually limits the replicative life span of somatic cells and is regarded as an ultimate tumour suppressor mechanism, eliminating cells that have accumulated genetic alterations. Telomerase, which has been found in over 85% of human cancers, elongates telomeres and may be required for tumorigenesis by the process of immortalisation. Malignant mesothelioma is an incurable malignancy with a poor prognosis. The disease becomes symptomatic decades after exposure to carcinogenic asbestos fibres, suggesting the long term survival of pre-malignant cell clones. This study investigated the presence of telomerase in pleural malignant mesothelioma, which may be the target for future anti-telomerase drugs. METHODS Telomerase activity was semiquantitatively measured in extracts from 22 primary pleural mesotheliomas, two benign solitary fibrous tumours of the pleura, four mesothelioma cell lines, and six short term mesothelial cell cultures from normal pleura using a non-isotopic dilution assay of the telomeric repeat amplification protocol. RESULTS Twenty of the 22 primary mesotheliomas (91%) and all tumour derived mesothelioma cell lines were telomerase positive. Different levels of enzyme activity were observed in the tumours of different histological subtypes. Telomerase activity could not be detected in the six normal mesothelial cell cultures or in the two mesotheliomas. Both benign solitary fibrous tumours showed strong telomerase activity. CONCLUSIONS Telomerase activity is found in a high proportion of mesotheliomas and anti-telomerase drugs might therefore be useful clinically. The results are consistent with the hypothesis that telomerase activity may be a feature of carcinogenesis in mesotheliomas and possibly in many other cancers.
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Affiliation(s)
- K Dhaene
- Department of Pathology, University of Antwerp, Wilrijk, Belgium
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Hübner R. Visuelle Welt: a Windows program for demonstrating visual-perception phenomena. Spat Vis 1997; 11:103-6. [PMID: 9304759 DOI: 10.1163/156856897x00122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The Windows program Visuelle Welt allows the demonstration of various visual phenomena such as geometrical-optical illusions, subjective contours, apparent movement, and Gestalt principles. One of the program's most interesting features is that the illusion-inducing context can be switched off, and in addition for many phenomena parameters can be varied interactively.
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Affiliation(s)
- R Hübner
- Institut für Psychologie, Technische Universität Braunschweig, Braunschweig, Germany.
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Hübner R, Högemann AM, Sunzel M, Riddell JG. Pharmacokinetics of candesartan after single and repeated doses of candesartan cilexetil in young and elderly healthy volunteers. J Hum Hypertens 1997; 11 Suppl 2:S19-25. [PMID: 9331000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Candesartan cilexetil is rapidly and completely hydrolysed to the active compound candesartan during absorption from the gastrointestinal tract. Candesartan is a potent, long-acting, selective angiotensin II AT1 receptor blocker. The pharmacokinetics of candesartan were investigated after single and repeated once-daily doses of candesartan cilexetil in the dose range 2-16 mg in both younger (19-40 years) and elderly (65-78 years) healthy volunteers in five studies. Blood pressure, heart rate, and hormones associated with the renin-angiotensin system, and safety of candesartan cilexetil administration were also assessed. Placebo comparisons were made in four studies. Frequent blood samples were collected after the first single dose of candesartan cilexetil, and during the last dosing interval after 1 week repeated once-daily administration. Serum and plasma were analysed for candesartan cilexetil, candesartan and its inactive metabolite, CV-15959, as well as angiotensin I and II, aldosterone, plasma renin activity (PRA) and angiotensin-converting enzyme (ACE) activity. The AUC and Cmax of candesartan showed dose-proportional increases in the dose range of 2-16 mg candesartan cilexetil after both single and repeated once-daily tablet intake, indicating linear pharmacokinetics in both younger and elderly healthy subjects. The pharmacokinetics did not change on repeated dosing and, as expected from the half-life of candesartan of approximately 9 h in younger subjects, there was almost no accumulation after repeated once-daily dosing. The time to peak candesartan concentrations after tablet intake was consistently approximately 4 h at all dose levels. Both Cmax and AUC of candesartan were increased after single and repeated once-daily dosing in the elderly compared to younger subjects by approximately 50%. However, no accumulation after repeated once-daily dosing were seen in the elderly. The half-life of candesartan in the elderly (9-12 h) was somewhat longer than in the younger healthy adult volunteers (approximately 9 h) and no gender-related differences in the disposition of candesartan were observed. Serum concentrations of CV-15959 were much lower than candesartan, and reached peak serum concentrations later, about 4-9 h after dose intake. The elimination of CV-15959 was somewhat slower than that of candesartan. Candesartan cilexetil, the prodrug to candesartan, was not measurable in serum. No differences in ACE activity or serum aldosterone concentrations were observed between subjects receiving candesartan cilexetil and placebo tablets. Plasma angiotensin I and II concentrations and PRA were augmented after single doses and further increased after 1 week repeated candesartan cilexetil dosing. Single and repeated doses of candesartan cilexetil were well tolerated in the younger and elderly volunteers. Only mild adverse events were recorded, with 'headache' as the most commonly reported event, and no increase in the number of reported adverse events was observed with higher doses of candesartan cilexetil. No clinically significant changes in respect to vital signs, physical examination, ECG, and clinical laboratory tests were observed.
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Affiliation(s)
- R Hübner
- Takeda Euro R&D Centre, Frankfurt/Main, Germany
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Elmfeldt D, George M, Hübner R, Olofsson B. Candesartan cilexetil, a new generation angiotensin II antagonist, provides dose dependent antihypertensive effect. J Hum Hypertens 1997; 11 Suppl 2:S49-53. [PMID: 9331007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Candesartan is a new generation angiotensin II type 1 receptor blocker, characterised by tight binding to and slow dissociation from the receptor. In order to delineate the dose-response curve for candesartan cilexetil (the orally administered prodrug), results from six European placebo-controlled, dose-response studies were pooled. These were of a double-blind, randomised, parallel group design, with a treatment duration of 4-12 weeks. A total of 1482 patients with mild to moderate primary hypertension were treated with candesartan cilexetil 2 mg (n = 80), 4 mg (n = 216), 8 mg (n = 455) or 16 mg (n = 294), or with placebo (n = 437). Blood pressure (BP) measurements were performed 24 h after dose. The differences in BP change (baseline vs end of the studies) between the placebo group and the groups treated with candesartan cilexetil were assessed using analysis of covariance and dose response curves were estimated by fitting the data to an Emax model. The placebo-corrected mean reductions in sitting diastolic BP were approximately 2.5 mm Hg with 2 mg, 4.5 mm Hg with 4 mg, 6 mm Hg with 8 mg, and 8 mm Hg with 16 mg of candesartan cilexetil. For sitting systolic BP, the placebo-corrected mean reductions were in the order of 5, 7, 10 and 12 mmHg, respectively, with 2, 4, 8 and 16 mg of candesartan cilexetil. The BP reductions were similar in the standing position with no indication of postural hypotension. Age or gender did not influence the BP response to candesartan cilexetil. In conclusion, candesartan cilexetil provides a clinically significant, dose-dependent antihypertensive effect in doses ranging from 4-16 mg once daily.
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Affiliation(s)
- D Elmfeldt
- Clinical R&D, Astra Hässle, Mölndal Sweden
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46
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Belcher G, Hübner R, George M, Elmfeldt D, Lunde H. Candesartan cilexetil: safety and tolerability in healthy volunteers and patients with hypertension. J Hum Hypertens 1997; 11 Suppl 2:S85-9. [PMID: 9331017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The tolerability and safety of candesartan cilexetil has been evaluated in over 5000 subjects enrolled into double-blind or open-label clinical studies. In double-blind clinical trials in patients with primary hypertension, candesartan cilexetil 2-16 mg once-daily was associated with a low incidence of adverse events and drug-related withdrawals, similar to placebo. The drug showed no evidence of dose-dependent adverse events and it was equally well tolerated by men and women and by elderly (> or =65 years) and younger (<65 years) patients alike. Candesartan cilexetil had no effect on blood glucose control or serum lipid profile in patients with type II diabetes. It was very well tolerated also when given in combination with hydrochlorothiazide or amlodipine and during long-term open-label therapy (up to 1 year). Candesartan cilexetil therefore possesses an excellent tolerability profile that extends to a wide variety of patients including the elderly and it does not aggravate co-existing risk factors such as hyperlipidaemia or glucose intolerance. It therefore appears to offer a better tolerated alternative to other commonly used antihypertensive agents.
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Affiliation(s)
- G Belcher
- Clinical Research and Drug Safety, Takeda Euro R&D Centre, Frankfurt/Main, Germany
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Abstract
There are many conditions in which identification proceeds faster for the global form of a hierarchical pattern than for it's local parts. Since the global form usually contains more lower spatial frequencies than do the local forms, it has frequently been suggested that the higher transmission rate of low spatial frequencies is responsible for the global advantage. There are also functional hemispheric differences. While the right hemisphere is better at processing global information, the left hemisphere has an advantage with respect to local information. In accordance with the spatial-frequency hypothesis, it has been speculated that this difference is due to a differential capacity of the hemispheres for processing low and high spatial frequencies. To test whether low spatial frequencies were responsible for the global advantage and/or for the observed hemispheric differences, two experiments were carried out with unfiltered and highpass-filtered compound-letter stimuli presented at the left, right, or center visual field. The first experiment, in which the target level was randomized in each trial block, revealed that low spatial frequencies were not necessary for either global advantage or for hemispheric differences. Highpass filtering merely increased the response times. In the second experiment, the target level was held constant in each block. This generally increased the speed of responding and produced interactions between filtering and global-local processing. It was concluded that both sensory and attentional or control mechanisms were responsible for global precedence and that the hemispheres differed with respect to the latter.
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Affiliation(s)
- R Hübner
- Technische Universität Braunschweig, Institut für Psychologie, Germany.
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Abstract
If the spatial-frequency of sinusoidal signals in a contrast-detection experiment varies randomly from trial to trial, then performance is decreased compared with that in a situation where it remains constant. This spatial-frequency uncertainty effect can more or less be compensated by presenting informative cues shortly before each trial. Single-band, as well as multiple-band models, have been proposed to explain the uncertainty and cuing effects. While the latter assume that under uncertainty multiple channels are monitored simultaneously, the former propose that in each trial a single, but sometimes inappropriate, channel is selected for monitoring. Until now it is open which of these models is valid. Therefore, psychometric functions were collected under different conditions of spatial-frequency uncertainty. It appears that the size of the uncertainty effect varies with spatial-frequency. This result can be explained by a multiple-band model, as computational analysis reveals.
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Affiliation(s)
- R Hübner
- Institut für Psychologie, Technische Universität Braunschweig, Germany
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Abstract
Detection experiments reveal that performance is decreased when the signal's spatial frequency varies unpredictably across trials compared with conditions where it is held constant. However, this effect can more or less be compensated by presenting cues shortly before each trial. To investigate the efficiency of different sensory and symbolic cue types a signal-detection experiment with spatial-frequency uncertainty was carried out. The inter-stimulus interval between cue and signal as well as for the sensory cue types, the spatial overlap between cue and signal, was varied. The results reveal appreciable efficiency differences. While some cues were only of little help, others reduced uncertainty almost entirely. However, the efficiency of cues which were identical to the signals was severely restricted by forward-masking effects when they were presented at the same position as the signal.
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Affiliation(s)
- R Hübner
- Psychologisches Institut, Technische Universität Braunschweig, Germany.
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